An overused and misused phrase popularized by The Big Band Theory. People have steadily increased its use and the ranges of its meaning, its original meaning was to accompany a prank or some sort of fooling. In modern times 'Bazinga' has been used as a sort of "Sounds good!" or a "Sweet".

Guy 1: "Yeah man I just got an A on that Biochemistry final!"
Guy 2: "Bazinga!"
Guy 1:"....I've lost all respect for you"

Bazinga is the word used by Dr. Sheldon Cooper off of the hilarious sitcom The Big Bang Theory. Bazinga can be used in place of such words and phrases such as Your mom, In your face, Face, and the That 70s Show word - Burn.

Sheldon Cooper: Of course not. Even in my sleep-deprived state, I’ve managed to pull off another one of my classic pranks. BAZINGA!